Missing folder in EHD after canceling "replace" file command

HELP! I am running low on memory, low on EHD space and I was trying to combine folders, because Lightroom was causing files to go missing due to the lack of memory. I was going to combine 2 folders and I hit "Replace" instead of "Merge" and quickly cancelled that action. BUT, in doing so, The folder I was going to add to is missing and so is the lightroom catalog! I'm searching all of my folders on my computer and I cannot find them. Please Help! I don't know what to do! The entire folder and all of it's subfolders are gone.